W02 sixteen wavelength-multiplexed channels over km of fiber. Figure 2 optlcal star network shows the optical spectrum at a given output of the star coupler. E-Lambdanet Corporation is creating new leading-edge-technologies on End-to-End Multi-wavelength Optical Fiber Communication Network Systems. Lambda switching (sometimes called photonic switching, or wavelength switching) is the technology used in optical networking to switch individual wavelengths of light onto separate paths for specific routing of information. In conjunction with technologies such as dense wavelength.


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The lambda router takes in a single wavelength of light from a specific fiber optic strand and recombines it into another strand that is set on a different path.

Lambda routers are being manufactured by a number of companies, including Ciena, Lucent, and Nortel.

WDM Technology and Issues in WDM Optical Networks

We aim to create an affluent society by lambdanet in optical network the lambdanet in optical network of our comprehensive strengths in these fields. In addition, optical fibers are more secure, compared to copper cables, from tapping as light does not radiate from the fiber, it is nearly impossible to tap into it secretly without detection and are also immune to interference and crosstalk.

By proper tuning of the local oscillator frequency fLO, the difference frequency fi -fLO of the desired channel is brought within the frequency range of a detector 42 which is a low pass optical filter and a square law converter.


The data signal carried by the selected carrier at lambdanet in optical network fi can thereafter be IF demodulated by the lambdanet in optical network The optical heterodyning of Bachus et al allows for very narrow channel spacing; 6 GHz or 0. However, optical heterodyning requires a narrow-band, continuously tunable laser for the local oscillator Bachus states that the laser must be stabilized in temperature to 0.

In order to suppress phase noise, the laser linewidth must be very narrow. Needless to say, these requirements put severe demands on the design of the local oscillator laser. As has been explained by Spencer in his review article on WDM systems entitled "State-of-the-art survey of multimode fiber optic wavelength division multiplexing" appearing in Proceedings of the SPIE, vol.

Many of the demultiplexers described by Ishio et al and by Spencer are complex, as is the demultiplexer of the Bachus et al system.

Lambda switching (photonic switching, or wavelength switching)

Except for the optical heterodyning, the number of channels is severely limited. Spencer teaches that few systems use optical filters as the wavelength discriminating device but they are instead used more for the purpose of improving signal to noise. The two main types of filters disclosed by Spencer in association with wavelength discrimination are interference filters lambdanet in optical network high or low pass dichroic filters.

One of the major drawbacks of the demultiplexers lambdanet in optical network by Spencer, by Kobrinski et al, and by Ishio et al is that the demultiplexed frequencies are physically fixed by the structure or at least the configuration of the demultiplexer.

OSA | High-bit-rate measurements in the LAMBDANET multiwavelength optical star network

Tunability is mostly discussed in conjunction with angular changes in physical optics. It thus becomes very difficult to build one demultiplexer lambdanet in optical network can be tuned to different frequencies. Such a tunability would allow detection of different ones of the data channels.

When tuning is achieved by physical movement of the diffraction grating or fibers, the tuning is necessarily slow. Furthermore, there is an inevitable amount of backlash in lambdanet in optical network adjustable opital components, which reduces the accuracy of the optical tuning.

The tunable optical filters of the prior art offer different lambdanet in optical network and disadvantages, as discussed below.

The Fabry-Perot or tunable etalon type of filter is desirable in that it is not dependent upon the polarization of the light and has a relatively low insertion loss of 2 to 3 dB.

Its finesse of 40 to is acceptable. However, its mechanical tuning is slow and its repeatability of tuning is very poor.

OPTNET: a cost-effective optical network for multiprocessors

This type of filter can be cascaded into two stages. The finesse is then increased to about but the insertion loss is raised to above 10 dB. The mechanical tuning then lambdanet in optical network slower and more difficult to control. An electro-optic type of optical filter relies on electronic tuning so that channel hopping can be done on the order of nanoseconds.

The tuning range of about 10 nm is not very good but the repeatability and fine tunability are acceptable.


The insertion loss of 4 to 6 dB is marginal. The biggest disadvantages of electro-optic filters are the small finesse of about 10 and the polarization dependency.


Semiconductor optical filters of the injection current type also provide nanosecond electronic tuning.